Field of the Disclosure
Embodiments of the present invention relate to an organic light emitting display device, and more particularly, to a top emission type organic light emitting display device.
Discussion of the Related Art
An organic light emitting display (OLED) device, which is a self-light emitting display device, has advantages of low power consumption, rapid response speed, high emission efficiency, high luminance and wide viewing angle.
According to the direction of light emitted from an organic light emitting device, the OLED device may be generally classified into a top emission type and a bottom emission type. In the bottom emission type, a circuit device is disposed between an emitting layer and an image displaying surface, which may lower an aperture ratio of the OLED device. In the top emission type, a circuit device is not disposed between an emitting layer and an image displaying surface, thus an aperture ratio can be improved when compared to the bottom emission type.
FIG. 1 is a cross sectional view of a related art top emission type OLED device.
As shown in FIG. 1, a thin film transistor layer (T) including an active layer 11, a gate insulating film 12, a gate electrode 13, an insulating interlayer 14, a source electrode 15, and a drain electrode 16 is provided on a substrate 10, and then a passivation layer 20 and a planarization layer 30 are sequentially provided on the thin film transistor layer (T).
Also, an anode electrode 40 and an auxiliary electrode 50 are provided on the planarization layer 30. The auxiliary electrode 50 is provided to lower a resistance of a cathode electrode 90. In the top emission type, light emitted from an organic emitting layer 80 passes through the cathode electrode 90. In this reason, the cathode electrode 90 is formed of a transparent conductive material, which causes the increase of resistance therein. In order to lower the resistance of the cathode electrode 90, the cathode electrode 90 is connected with the auxiliary electrode 50.
On the anode electrode 40 and the auxiliary electrode 50, a bank 60 is provided to define a pixel region. Also, the organic emitting layer 80 is provided in the pixel region defined by the bank 60.
If the auxiliary electrode 50 is covered by the organic emitting layer 80, an electrical connection between the cathode electrode 90 and the auxiliary electrode 50 becomes difficult. Thus, in order to prevent the auxiliary electrode 50 from being covered by the organic emitting layer 80, a partition 70 is provided on the auxiliary electrode 50. The partition 70 is spaced apart from the bank 60, whereby the auxiliary electrode 50 and the cathode electrode 90 are connected to each other via a gap space between the partition 70 and the bank 60.
The partition 70 can include a first partition 71 and a second partition 72, in which the partition 70 is formed in a structure of eaves. Thus, according as the organic emitting layer 80 with superior straightness for the properties of process is blocked by the partition 70, it is possible to prevent the organic emitting layer 80 from being permeated into the gap space between the partition 70 and the bank 60. Meanwhile, the cathode electrode 90 with inferior straightness for the properties of process permeates into the gap space between the partition 70 and the bank 60, and is then connected to the auxiliary electrode 50.
In the related art top emission type OLED device, an electrical connection between the cathode electrode 90 and the auxiliary electrode 50 is made in the gap space between the partition 70 and the bank 60. However, if there is a mis-alignment during a process of forming the partition 70, it can cause a decrease in the contact area between the cathode electrode 90 and the auxiliary electrode 50. This will be described with reference to FIGS. 2A to 2C.
FIGS. 2A to 2C are plane views illustrating the electrical connection between the cathode electrode 90 and the auxiliary electrode 50 in the related art top emission type OLED device.
FIG. 2A illustrates a situation in which a mis-alignment does not occur between the first partition 71 and the second partition 72, and FIG. 2B and FIG. 2C illustrates a situation in which a mis-alignment occurs between the first partition 71 and the second partition 72 due to the second partition 72 being shifted to the left or right.
As shown in FIG. 2A, when there is no mis-alignment between the first partition 71 and the second partition 72, it is possible to secure a predetermined design in a dotted-line area corresponding to a contact area between the cathode electrode 90 and the auxiliary electrode 50. For reference, the dotted-line area corresponds to the contact area between the cathode electrode 90 and the auxiliary electrode 50 by the cathode electrode 90 being permeated into the area below the second partition 72.
However, as shown in FIGS. 2B and 2C, if there is the mis-alignment between the first partition 71 and the second partition 72, the dotted-line area corresponding to the contact area between the cathode electrode 90 and the auxiliary electrode 50 is to be smaller than the predetermined design. That is, the cathode electrode 90 has a limitation on permeation into the area below the second partition 72, whereby there is a vacancy where the cathode electrode 90 is not deposited in the area caused by the shifted second partition 72, to thereby decrease the contact area between the cathode electrode 90 and the auxiliary electrode 50.
If there is a mis-alignment between the first partition 71 and the second partition 72, the contact area between the cathode electrode 90 and the auxiliary electrode 50 is decreased in size, which might increase the resistance in the cathode electrode 90.